The present invention relates to machined part inspection systems and more particularly to an inspection system which compares the actual locations of a plurality of features and the corresponding nominal locations and allowable tolerances of the plurality of features to determine when the parts should be rejected because a feature fails to fall within the allowable tolerance for the feature.
Currently, the nominal locations and allowable tolerances of a pattern of features on a machined part are generally dimensioned relative to a coordinate system established by the part itself. A typical example is a bolt-hole circle with the bolt holes and tolerances being specified from the center of the bolt-hole circle. In the past, for inspection purposes, the inspection system would establish an arbitrary coordinate system by placing the origin at the center of one bolt-hole and aligning the part so that one of the axes would pass through the center of a second bolt-hole. By the very nature of this inspection system, the erroneous assumptions had to be made that the origin bolt-hole was drilled with no error in location and that the bolt hole at the axis was drilled with no error in location tangential to the origin bolt-hole. Thus, errors in the location of the origin or axis bolt hole would lead to the costly rejection of parts which were actually within the tolerances specified relative to the center of the bolt-hole circle.